Cooling fan control device

ABSTRACT

The cooling capacity of a cooling fan is made lower when a vehicle was not running while towing a trailer than when the vehicle was running while towing the trailer immediately before the end of a service of the vehicle, in activating the cooling fan after the end of the service.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2021-118174 filed on Jul. 16, 2021, incorporated herein by reference in its entirety.

BACKGROUND 1. Technical Field

The disclosure relates to the control of operation of a cooling fan that introduces outside air into a prime mover room of a vehicle.

2. Description of Related Art

Japanese Unexamined Patent Application Publication No. 2001-317354 (JP 2001-317354 A) discloses an art of activating a radiator fan to introduce outside air into an engine room when the temperature in the engine room is high while a vehicle runs at low speed or is stopped. Besides, there is known an art of activating a radiator fan to introduce outside air into an engine room for a predetermined time after the end of a service of a vehicle.

SUMMARY

When a cooling fan such as a radiator fan is activated after the end of a service of a vehicle, the amount of electric power stored in a battery decreases. It is an object of the disclosure to restrain the amount of electric power stored in a battery from decreasing due to activation of a cooling fan after the end of a service of a vehicle.

A cooling fan control device according to the disclosure controls the operation of a cooling fan that introduces outside air into a prime mover room of a vehicle, and makes the cooling capacity of the cooling fan lower when the vehicle was not running in a towing mode than when the vehicle was running in the towing mode immediately before the end of a service, in activating the cooling fan after the end of the service.

If the vehicle was not running in the towing mode in the immediately preceding service, the amount of electric power stored in a battery can be restrained from decreasing due to activation of the cooling fan after the end of the service.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, advantages, and technical and industrial significance of exemplary embodiments of the disclosure will be described below with reference to the accompanying drawings, in which like signs denote like elements, and wherein:

FIG. 1 is a view schematically showing a vehicle that tows a trailer;

FIG. 2 is a block diagram showing the configuration of a cooling device that cools the interior of an engine room; and

FIG. 3 is a flowchart regarding the cooling of the interior of the engine room after the end of a service.

DETAILED DESCRIPTION OF EMBODIMENTS

One of the embodiments of the disclosure will be described hereinafter with reference to the drawings. FIG. 1 is a view schematically showing a trailer 12 that is towed by a vehicle 10. A trailer hitch 13 is provided at a rear end of the vehicle 10. The vehicle 10 and the trailer 12 are coupled to each other by joining a coupling portion of the trailer 12 to the trailer hitch 13.

An engine 14 serving as a prime mover that drives the vehicle 10 is mounted in a front portion of the vehicle 10. A space in which the engine 14 is accommodated is referred to as an engine room 16. The vehicle 10 is equipped with a cooling device 18 that introduces outside air into the engine room 16 to cool the engine room 16, with a view to restraining the temperature in the engine room 16 from rising due to the generation of heat by the engine 14. The cooling device 18 has cooling fans 20 and 22 that deliver outside air into the engine room 16. The cooling fan 20 may be a radiator fan that delivers air to a radiator 24 that discharges the heat of coolant for the engine 14. The cooling fan 22 may be a capacitor fan that delivers air to a capacitor 26 of an air-conditioning device. The cooling fans 20 and 22 are electric fans, and are driven by electric power from a battery that supplies electric power to electric components and the like of the vehicle 10. The operation of the cooling fans 20 and 22 is controlled by a cooling fan control device 28. The cooling fan control device 28 determines whether or not the interior of the engine room 16 needs to be cooled based on detection values of some sensors, and controls the operation of the cooling fans 20 and 22 based on this determination. Incidentally, the cooling fan control device 28 is depicted outside the vehicle 10 in FIG. 1 , but is actually installed in, for example, a passenger compartment of the vehicle 10.

The cooling device 18 cools the interior of the engine room 16 when the temperature in the engine room 16 is high even after the end of a service of the vehicle 10. A determination on a service of the vehicle 10 is made in accordance with a state of an ignition switch 30. One service extends from a timing when the ignition switch 30 is turned on to a timing when the ignition switch 30 is turned off. It is determined that the service of the vehicle 10 is ended when the ignition switch 30 that is on is turned off.

It is determined whether or not the interior of the engine room 16 should be cooled after the end of the service, based on a temperature of coolant for the engine 14, an outside air temperature, and the history of a rotational speed of the engine 14. The temperature of coolant is detected by a coolant temperature sensor 32, the outside air temperature is detected by an outside air temperature sensor 34, and the rotational speed of the engine 14 is detected by a rotational speed sensor 36.

Besides, it is determined whether or not the vehicle 10 was towing the trailer 12 in an immediately preceding service. The operation of the cooling fans 20 and 22 after the end of the service is controlled in accordance with this determination. In concrete terms, the cooling capacity of the cooling fans 20 and 22 is controlled to be lower when the vehicle 10 was not towing the trailer 12 than when the vehicle 10 was towing the trailer 12 in the immediately preceding service. The running of the vehicle 10 in a towing mode is detected by a tow sensor 38 provided on the trailer hitch 13.

FIG. 2 is a block diagram showing the configuration of the cooling device 18. The ignition switch 30 is provided close to a driver seat. When a driver turns the ignition switch 30 on, the vehicle 10 becomes capable of running. Besides, when the driver turns the ignition switch 30 off, the vehicle 10 is not allowed to run. The coolant temperature sensor 32 is provided in a flow passage for coolant circulating through the engine 14 and the radiator 24, and detects a temperature of the coolant. The outside air temperature sensor 34 is provided close to an inlet such as a front grille through which outside air flows into the engine room 16, and detects a temperature of outside air introduced into the engine room 16. The rotational speed sensor 36 is provided close to an element that rotates in a certain relation to a crankshaft, for example, a flywheel of the engine 14, and detects a rotational speed of the crankshaft. The tow sensor 38 is provided on the trailer hitch 13, and detects a force that is applied to the trailer hitch 13 when the trailer 12 is towed.

The cooling fan control device 28 has an arithmetic processing device that operates according to a predetermined program, and a storage unit 40 that temporarily stores the program and a processing result. The cooling fan control device 28 makes a determination on the start and end of a service, based on a signal from the ignition switch 30. Accordingly, the cooling fan control device 28 is configured to function as a service end determination unit 42 that makes a determination on the end of a service of the vehicle 10.

The cooling fan control device 28 determines whether or not the engine room 16 needs to be cooled after the end of a service, based on detection values of the coolant temperature sensor 32, the outside air temperature sensor 34, and the rotational speed sensor 36. It is determined whether or not cooling is necessary, based on whether or not the temperature of coolant is equal to or higher than a predetermined value, the temperature of outside air is equal to or higher than a predetermined value, and there is a high-rotation history in which the rotational speed of the engine 14 became equal to or higher than a predetermined value immediately before the end of the service. The rotational speed of the engine 14 is monitored during the service. The number of times of the attainment of a predetermined rotational speed or more or the time of duration of the driving of the vehicle 10 at a speed equal to or higher than the predetermined rotational speed is stored in the storage unit 40. When at least one of these values becomes equal to or larger than a predetermined value, it is determined that there is a high-rotation history. The cooling fan control device 28 is configured to function as a cooling necessity determination unit 44 that determines whether or not the engine room 16 needs to be cooled after the end of a service.

The cooling fan control device 28 determines whether or not the vehicle 10 was running while towing the trailer 12 immediately before the end of a service, based on a detection value of the tow sensor 38, at the end of the service. The detection of the tow sensor 38 is monitored during the service. When the detection value exceeds a predetermined value, this excess is stored into the storage unit 40. If the detection value of the tow sensor 38 exceeded the predetermined value at least once immediately before the end of the service, it is determined that the vehicle 10 was running in the towing mode, at the end of the service. The cooling fan control device 28 is configured to function as a towing-mode running determination unit 46 that determines whether or not the vehicle 10 was running in the towing mode immediately before the end of the service.

When the cooling necessity determination unit 44 determines that the engine room 16 needs to be cooled, the cooling fan control device 28 performs drive control of the cooling fans 20 and 22. Furthermore, when the towing-mode running determination unit 46 determines that the vehicle 10 was running in the towing mode in the immediately preceding service, the cooling fan control device 28 performs drive control of the cooling fans 20 and 22 at high capacity. When the towing-mode running determination unit 46 determines that the vehicle 10 was not running in the towing mode in the immediately preceding service, the cooling fan control device 28 performs drive control of the cooling fans 20 and 22 at low capacity. The change in capacity of the cooling fans 20 and 22 can be realized by changing the number of cooling fans to be driven. Both the cooling fans 20 and 22 are driven at the time of high capacity, whereas only one of the cooling fans 20 and 22 is driven at the time of low capacity. Besides, the cooling capacity can also be changed by changing the rotational speed of the cooling fans 20 and 22. The two cooling fans 20 and 22 are driven at high rotation at the time of high capacity, and are driven at low rotation at the time of low capacity. Besides, only one of the cooling fans, for example, only the cooling fan 20 that is the radiator fan can be driven at the time of cooling after the end of a service. In this case, the cooling capacity is changed by changing the rotational speed of the cooling fan 20. The cooling fan control device 28 is configured to function as a fan drive control unit 48 that performs drive control of the cooling fans 20 and 22.

FIG. 3 is a view showing the flow of control regarding the cooling of the engine room 16 after the end of a service. When the ignition switch 30 is turned off to end the service (S100), it is determined whether or not the temperature of coolant is equal to or higher than the predetermined value (S102). If the temperature of coolant is equal to or higher than the predetermined value, it is then determined whether or not the temperature of outside air is equal to or higher than the predetermined value (S104). If the temperature of outside air is equal to or higher than the predetermined value, it is further determined whether or not there is a high-rotation history in which the engine 14 was operated at high rotation in an immediately preceding service (S106). If there is a high-rotation history, it is determined whether or not the vehicle 10 was running in the towing mode in the immediately preceding service (S108). If the vehicle 10 was running in the towing mode, drive control is performed such that the cooling capacity of the cooling fans 20 and 22 becomes high (S110). If the vehicle 10 was not running in the towing mode, drive control is performed such that the cooling capacity of the cooling fans 20 and 22 becomes low (S112). After the lapse of a predetermined time from the end of the service, the cooling fans 20 and 22 are stopped to end the control (S114). If it is determined that the condition for determination is not fulfilled in each of steps S102, S104, and S106, the control is ended without driving the cooling fans 20 and 22.

When the vehicle 10 runs in the towing mode, the frequency with which the engine 14 is operated at high load becomes high, and the temperature of the engine 14 becomes high. When the wind resulting from the running of the vehicle 10 stops entering the engine room 16 after the end of a service, the heat from the engine 14 accumulates in the engine room 16, and the temperature in the engine room 16 rises in some cases. In consequence, in the case where the engine room 16 is cooled after the end of the service, if the vehicle 10 was running in the towing mode, the cooling fans 20 and 22 are operated at high capacity to introduce a large amount of outside air and further cool the engine room 16. On the other hand, if the vehicle 10 did not run in the towing mode, the temperature of the engine 14 is not considered to be very high, so the cooling fans 20 and 22 are operated at low capacity to reduce the electric power consumed to drive the cooling fans 20 and 22. Thus, the amount of electric power stored in the battery can be restrained from decreasing.

The prime mover may not necessarily be a single engine, but may be a hybrid prime mover as a combination of an engine and an electric motor, or a single electric motor. Instead of providing the radiator and the capacitor with the cooling fans separately, a common cooling fan may be provided for both the radiator and the capacitor such that the wind generated by this single cooling fan hits both the radiator and the capacitor. Besides, each of the cooling fans may not necessarily be a radiator fan or a capacitor fan, but may be any fan that can introduce outside air into the prime mover room. Besides, the temperature of coolant is adopted to represent the temperature of the prime mover, but the disclosure is not limited thereto. The temperature of a surface of the prime mover or the temperature of a predetermined region inside the prime mover may be adopted instead. A determination on the necessity of cooling after the end of a service may be made based on one or two of the temperature of coolant, the temperature of outside air, and the presence of a high-rotation history. 

What is claimed is:
 1. A cooling fan control device that controls operation of a cooling fan that introduces outside air into a prime mover room of a vehicle, and that makes cooling capacity of the cooling fan lower when the vehicle was not running in a towing mode than when the vehicle was running in the towing mode immediately before end of a service of the vehicle, in activating the cooling fan after end of the service. 